This invention relates generally to a coupling for connecting sections of pipe, and more particularly, to a friction sealed coupling assembly for connecting sections of pipe such as high pressure pipe.
High pressure pipe has a number of practical applications. For example, high pressure pipe is used for oil well casings, gas piping and high pressure water piping. To extend a length of such piping, or to repair a break in a section of piping, respective sections must be joined together, end-to-end. Small diameter piping can be joined by threading the outer diameter of the adjoining ends of the pipe sections and fitting a threaded sleeve onto the ends to connect the respective pipe sections. This method is not, however, practical for large diameter, high pressure pipe, such as oil well casing, large diameter water pipes or the like. Presently sections of such large diameter pipe are connected with a coupling having an internal, non-metallic cup seal or gasket intended to prevent fluid from leaking between the seal and the outside wall of the pipe. Such couplings employ a holding mechanism, such as a collar or flange, at the end of the section of pipe to be joined. Adjustment screws extend from flange to flange, for example, to draw the ends of the pipe together and position the pipe concentric to the coupling. This is an unsatisfactory procedure that relies on the seal to prevent leakage. This method can result in a relatively flexible or deformable joint that can rupture and leak when subjected to torsional forces. Furthermore, mispositioning or damage to the seal is not detected until after the pipe is pressurized. Seals or gaskets, moreover, reduce the internal diameter of the joint, thereby reducing fluid flow into through the pipe.
Joints connecting high pressure pipe sections can be welded. However, welding is labor intensive and expensive. Heavy welds can protrude into the joint, again reducing the internal diameter. Moreover, small holes in the welds may not be detected until after the pipe is pressurized. To prevent such problems, the wells are x-rayed, another time consuming and expensive procedure. Finally, welding and x-raying joints of high pressure pipe under water is time consuming, expensive, and, at times, impractical.
The present invention recognizes and solves the problems associated with connecting sections of pipe, particularly high pressured pipe. The present invention does not rely on a non-metallic seal to prevent leakage but connects the sections of pipe together by drawing the sections together inside a friction sealed steel assembly.